×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Effective width using AISC 13th edition

Effective width using AISC 13th edition

Effective width using AISC 13th edition

(OP)
I am using Table B4.1 to determine my effective width.  I have a 12guage steel plate, 120"x120".  The plate is stiffened with 3"x 1/4" bars at 24"on center.  The final section will resemble the example detail in the table for cases 7 and 8.  However, my question is: do I double the b value when I calculate my final section properties?  I am confused because in Section B4, paragraph 2, note c, for diaphragm plates, it states that the width (b) is the distance between the adjacent lines of fasteners or welds.  This gives me a large section modulus and thus a large capacity.  And the (b/t) ratio exceeds the limits noted in the table.  Any clarification would be greatly appreciated.  Thanks.  

RE: Effective width using AISC 13th edition

You should check as per the case 14 IF the stiffeners were to prevent entirely against local buckling out of the plane of the plate buckling at the seams; since it may not be the case,said otherwise, the stiffness of the stiffeners has a say in the ability of the stiffened plate to bear load (along the length of the stiffeners). Essentially you need to check an orthotropic plate in compression and maybe the code is not giving the more convenient info to that purpose.

Yo can see how to proceed in Galambos IV p. 155, p. 255, that I find of more direct applicability than what quoted in Galambos V.

To make the point I attach jpg printout of one Mathcad 2000 worksheet by one method based in that reference. Were concomitant shear stresses present the limit stress in the check should be reduced.

Note also that you can quite easily model the thing in FEM, RISA and onwards, include some initial imperfections if required and if the thing remains stable, P-Delta included, (with the proper material stiffness reduction if required) you will get a safe design.

I may add some other worksheet later on related issues.

RE: Effective width using AISC 13th edition

(OP)
thanks for the information.  

RE: Effective width using AISC 13th edition

nuche1973,

I don't think you have the correct case for the 12 ga plate.  It seems to me it is more like Case 10 or Case 14 where a plate under compression is stiffened at each edge.  In those cases, b/t is limited to 1.49√(E/Fy) and b is the clear distance between stiffeners.

BA

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources